m 


GB 
2405 
U3 
EART 


UC-NRLF 

■■■ 


/'BERKEtev^ 

LIBRARY 


UNIVER.S.'TY  OF 
ALIFORNIA 


Vi£ 


SCIENCES 
LIBRARY 


m 


University  of  Texas  Bulletin 


No.  1821:      April  10,  1918 


/2 


See 


^Fossil  Ice  Crystals 

An  Instance  of  the  Practical  Value  of 
"Pure  Science" 


Bureau  of  Economic  Geology  and  Technology 

Division  of  Ek:ononiic  Geology 

J.  A.  Udden,  Director  of  the  Bureau  and  Head  of  the  Division 


Published  by  the  University  six  times  a  month  and  entered 
aecond-class  matter  at  the  postoffice  at 
AUSTIN,  TEXAS 


Publications  of  the  University  of  Texas 

Publications  Committee : 

F.  W.  Graff  R.  H.  Griffith 

J.  M.  Bryant  J.  L.  Henderson 

D.  B.  CASTEEL  I.  P.  HiLDEBRAND 

Frederic  Duncalf   E.  J.  Mathews 

The  University  publishes  bulletins  six  times  a  month,  so 
numbered  that  the  first  two  digits  of  the  number  show  the 
year  of  issue ;  the  last  two  the  position  in  the  yearly  series. 
(For  example,  No.  1701  is  the  first  bulletin  of  the  year  1917.) 
These  comprise  the  official  publications  of  the  University, 
publications  on  humanistic  and  scientific  subjects,  bulletins 
prepared  by  the  Department  of  Extension  and  by  the  Bureau 
of  Municipal  Research  and  Reference,  and  other  bulletins 
of  general  educational  interest.  With  the  exception  of 
special  numbers,  any  bulletin  will  be  sent  to  a  citizen  of 
Texas  free  on  request.  All  communications  about  Univer- 
sity publications  should  be  addressed  to  the  Chairman  of 
the  Publications  Committee,  University  of  Texas,  Austin. 


University  of  Texas  Bulletin 

No.   1821:      April  10,  1918 


Fossil  Ice  Crystals 

An  Instance  of  the  Practical  Value  of 
''Pure  Science" 


Bureau  of  Economic  Geology  and  Technology 

Division  of  Economic  Geology 

J.  A.  Udden,  Director  of  the  Bureau  and  Head  of  the  Division 


Published  by  the  University  six  times  a  month  and  entered  as 

second-class  matter  at  the  postoffice  at 

AUSTIN,  TEXAS 


The    benefits    of    education    and    of  'J 
useful    knowledge,    generally    diffused 

through    a    community,    are    essential  ; 

to  the  preservation  of  a  free  govern-  j 

ment.  \ 

Sam   Houston  \ 


Cultivated  mind  is  the  guardian 
genius  of  democracy.  .  .  .  It  is  the 
only  dictator  that  freemen  acknowl- 
edge and  the  only  security  that  free- 
men  desire. 

Mirabeau    B.    Lamar 


1> 


FOSSIL  ICE  CRYSTALS  "    y^ 

By  J.  A.  Udden  {yflf-A 

I 

AN  INSTANCE  OF  THE   PRACTICAL   VALUE   OF   "PURE   SCIENCE" 

The  practical  value  of  the  service  of  the  geological  pro- 
fession is,  with  every  year,  being  more  and  more  appre- 
ciated, especially  among  people  who  are  developing  the 
mineral  resources  of  our  country.  Nevertheless,  we  still 
hear  men  who  speak  of  geologists  as  theorists  that  render 
our  profitable  industries  but  little  assistance.  It  is  true  that 
much  of  the  work  that  geologists  do  has  but  a  remote  bear- 
ing on  practical  questions.  The  fact  is  that  in  geology,  as 
in  other  sciences,  one  can  never  know  when  a  purely  scien- 
tific observation  may  turn  out  to  have  a  practical  applica- 
tion. Paleontologists  who  study  the  minutest  details  of  fos- 
sils have  been  held  up  as  impractical  people,  even  though 
their  science  has  more  than  once  proved  to  be  of  the  greatest 
practical  importance  for  the  finding  of  valuable  natural  de- 
posits. Certainly  those  who  have  been  most  prominent  in 
the  promotion  of  paleontology  as  a  science  have  seldom,  if 
ever,  had  any  economic  motive  in  the  pursuit  of  their  work. 
I  think  the  same  is  true  of  our  leading  petrographers.  I 
believe  that  the  men  who  have  advanced  the  science  of 
geology  most,  have  seldom  contributed  much  to  the  prac- 
tical application  of  the  principles  they  have  discovered. 
Much  scientific  work  naturally  appears  unprofitable  or  use- 
less to  the  uninitiated.  I  shall  here  relate  a  case  that  sug- 
gests how  entirely  wrong  it  may  be  to  regard  as  of  no 
economic  value  any  geologic  fact,  however  insignificant  it 
may  appear. 

In  the  summer  of  1890  I  took  occasion  to  make  a  trip  to 
the  Black  Hills  in  South  Dakota  in  order  to  profit,  as  I 
could,  by  a  few  weeks'  tramping  in  this  interesting  region. 
Going  one  day  in  a  southwest  direction  from  Minnekahta, 
to  look  for  fossil  cycads,  I  stumbled  on  a  block  of  sandstone 
with  a  rather  smooth  surface  on  which  were  some  peculiar 


104C8 


4  University  of  Texas  Bulletin 

markings,  such  as  I  had  never  seen  figured  or  described. 
The  rock  was  evidently  a  block  from  the  Dakota  sandstone. 
Its  smooth  upper  surface,  which  represented  a  bedding  plane, 
was  covered  with  a  thin  coating  of  silt  or  fine  clay  which 
adhered  to  the  block.  The  markings  were  in  this  clay. 
They  were  straight,  shallow  grooves  from  one-half  to  two 
inches  in  length,  and  from  one-sixteenth  to  one-eighth  inch 
in  width.  They  were  joined  into  patterns  in  which  some 
sprang  out  from  the  sides  of  others  and  again  themselves 
sent  out  other  branches.  Some  crossed  each  other.  I  no- 
ticed that  there  was  a  quite  uniform  angle  of  divergence  in 
these  branches,  and  I  was  able  to  make  out  that  this  usual 
angle  was  about  sixty  degrees.  I  also  noted  that  the  grooves 
narrowed  to  sharp  points.  Somehow,  immediately  I  con- 
cluded that  the  cracks  were  the  result  of  ice  crystals,  and 
I  at  once  saw  the  propriety  of  frozen  water  having  existed 
in  an  age  during  which  deciduous  trees  began  to  appear. 
This  was  theory.  We  have  since  that  time  learned  to  know 
that  cold  climates  far  antedate  the  coming  of  the  dicotyle- 
dons. 

As  I  had  no  suitable  photographic  equipment,  I  took  pains 
to  make  accurate  drawings  of  a  part  of  the  pattern  as  it 
appeared  on  the  rock.  My  original  drawing  is  shown  in 
Plate  I.  A  brief  description  of  these  markings  was  later 
furnished  in  the  Scientific  American,  of  February  19,  1895. 

It  took  me  some  years  to  find  any  similar  markings  again. 
In  the  early  spring  of  1903  I  had  occasion  to  make  a  visit 
to  Mexico,  when  I  spent  a  half  day  in  Ojinaga,  which  is  a 
little  village  south  of  Presidio,  in  Texas,  on  the  Mexican  side 
of  the  river.  Some  sidewalks  in  this  little  village  are  built 
of  flags  of  limestone  belonging  to  the  Eagle  Ford  formation. 
To  my  great  delight  I  found  some  of  these  slabs  having 
precisely  the  same  kind  of  markings  that  I  had  noted  on  the 
sandstone  in  Dakota.  Naturall}^  I  attached  some  importance 
to  the  fact  that  the  Eagle  Ford  corresponds  quite  closely 
in  age  to  that  of  the  Dakota  sandstone.  Both  were  maae 
at  about  the  beginning  of  the  upper  Cretaceous  age.  I 
noticed  here  a  considerable  variation  in  the  closeness  of 
the  patterns  of  the  markings.  Occasionally  they  were  found 
as  separate  single  lines,  several  inches  removed  from  each 


Fossil  Ice  Crystals  5 

other;  and  on  other  rocks  they  would  be  found  crossing  in 
close  networks.  In  the  summer  of  1904  I  again  found  my 
ice  markings  on  a  layer  of  arenaceous  limestone  in  the  same 
formation  in  the  Big  Bend  country  in  Texas.  This  time  I 
collected  some  specimens  which  were  subsequently  photo- 
graphed. One  of  these  photographs  is  shown  in  Plate  II. 
Again  in  1906  I  noticed  the  same  markings  on  some  thin 
sandy  flags  which  occur  in  the  Del  Rio  clay  near  the  city  of 
Del  Rio.  In  this  case  the  needle-like  crystals  were  somewhat 
more  slender  than  those  previously  seen,  and  some  were 
slightly  curved  and  somewhat  more  elongated.  These  of 
course  interested  me  as  showing  the  occurrence  of  freezing 
temperatures  no  doubt  at  a  somewhat  earlier  time  than  that 
pertaining  to  my  previous  observations. 

During  all  these  years  my  residence  was  in  Illinois,  and 
I  was  naturally  watching  for  similar  markings  in  recent 
mud,  resulting  from  late  and  early  frosts.  I  found  them  in 
the  fall  of  1909.  At  this  time  some  excavations  were  being 
made  in  the  loess  in  Rock  Island,  when  some  rains  fell  in 
the  late  fall.  These  rains  evidently  happened  to  give  the 
mud  the  amount  of  moisture  necessary  for  such  crystals  to 
develop,  as  the  ground  froze.  The  rains  had  washed  the 
loess  extensively,  and  I  found  a  number  of  places  where  it 
lay  redistributed,  with  a  fairly  smooth  surface.  It  was 
evident  that  the  moisture  content  of  the  ground,  together 
with  the  temperature  conditions,  determined  the  size 
and  the  closeness  of  the  frozen  patterns.  In  places 
the  crystals  were  long  and  slender,  in  others  they 
were  short  and  stout.  At  some  points  they  were  straight 
and  in  others  slightly  curved.  Here  and  there  the  patterns 
were  close  enough  to  resemble  the  fine  lines  which  we  some- 
times notice  in  the  hoarfrost  on  windowpanes.  In  other 
places  the  crystals  occurred  in  radiating  groups,  and  else- 
where they  would  form  scattered  separate  units.  For 
preserving  a  record  of  what  I  saw,  I  poured  plaster  over 
several  patterns  and  had  these  casts  photographed,  as  ap- 
pears in  Plates  VIII.  IX,  X.    Placing  these  side  by  side  with 


6  Universiti/  of  Texan  Bulletin 

the  photographs  of  the  patterns  I  have  photographed  from 
the  Eagle  Ford,  it  appears  to  me  that  no  doubt  can  be  left 
as  to  the  origin  of  the  markings  found  in  the  fossil  state. 

Recently  I  have  found  that  these  ice  crystal  marks  are 
quite  common  at  one  horizon  in  the  Eagle  Ford  beds  of 
Brewster  County,  in  Texas.  There  is  also  a  layer  in  which 
they  can  be  usually  seen  in  the  vicinity  of  Austin,  Texas. 
This  lies  about  twenty-five  feet  below  the  Austin  Chalk, 
near  Austin.  A  like  layer  occurs  about  100  feet  below  the 
Austin  Chalk  in  the  Big  Bend  country.  Here  I  have  found 
the  markings  in  localities  thirty  miles  apart.  They  occur 
at  the  north  point  of  Mariscal  Mountain  and  in  a  number 
of  places  near  the  Fossil  Knobs  and  on  the  Chisos  Mining 
Company  property  at  Terlingua. 

Unprofitable  as  observations  on  such  a  simple  matter  as 
this  may  seem,  I  find  that  other  geologists  have  given  it 
some  attention.  Quite  recently,  Dr.  John  M.  Clarke*  has 
figured  slabs  showing  what  has  been  described  as  Fucoides 
graphica,  by  Hall.  The  markings  figured  by  Professor 
Clarke  are  undoubtedly  of  the  same  kind  as  those  I  have 
found  in  the  Eagle  Ford.  They  occur  in  the  Upper  Devonian 
in  New  York.  I  also  find  that  the  formation  of  ice  crystals 
in  wet  mud  has  been  observed  in  the  clays  about  Boston 
by  Marbut  and  Woodworth.**  Other  observations  of  simi- 
lar recent  markings  are  said  to  have  been  made  by  some 
English  geologists. 

To  "practical  people"  it  may  indeed  appear  that  no  more 
unprofitable  or  more  idle  curiosity  could  be  indulged  in, 
than  making  observations  on  what  kind  of  crystals  are 
formed  when  water  freezes  in  mud.  I  must  confess  that 
my  own  first  observations  had  no  motive  whatever,  except 
for  the  desire  to  know  something  new ;  and  I  never  ex- 
pected that  anything  I  could  learn  about  these  fossil  marks 
would  ever  turn  out  to  have  any  practical  application,  at 
least  not  in  my  own  work. 


*  Strand  and  undertow  markings,  etc.,  New  York  State  Museum, 
Bulletin  No.  196,  April  1,  1917,  pp.  199-210;  pi.  20-23. 

**Brick  clays  of  Rhode  Island,  Massachusetts;  Marbut  and  Wood- 
worth,  U.  S.  Geol.  Survey,  17th  Ann.  Rep.,  Pt.  1,  p.  992. 


F^ossil  Ice  Crystals  7 

But  it  has  turned  out  differently.  For  some  time,  I  have 
been  called  upon  occasionally  to  advise  with  regard  to  the 
finding  of  the  ore  in  one  of  our  quicksilver  mines  in  West 
Texas.  It  is  now  a  well  established  fact  that  the  distribu- 
tion of  the  ore  in  this  mine,  and  I  believe  in  the  entire 
Terlingua  district,  bears  a  definite  relation  to  geological 
horizons.  Successful  mining  requires  search  in  these 
horizons.  The  cinnabar,  as  it  appears,  has  accumulated  in 
greatest  quantity  under  impervious  rocks  such  as  shales 
and  marls  along  planes  that  separate  these  from  underlying 
rocks  of  more  open  texture,  mostly  limestones.  The  ore  has 
clearly  come  from  below  and  has  risen  through  fissure 
planes,  which  in  some  cases  separate  large  blocks  of  the 
Cretaceous  formations.  The  best  ore  has  been  found  under 
the  basal  part  of  the  Boquillas  flags,  and  under  the  Del  Rio 
clay  in  the  upper  part  of  the  Georgetown  limestone.  The 
workings  must  be  so  arranged  in  the  mine  that  these  hori- 
zons can  be  entered  on  both  sides  of  a  fault  fissure.  The 
problem  of  locating  the  depth  of  the  desirable  horizons  in 
the  mine  in  question  would  be  easy  enough,  if  it  were  not 
for  the  fact  that  the  outcropping  rocks  consist  of  a  series 
of  sediments  with  few  characteristic  fossils.  Most  of  the 
fossils  which  occur  extend  through  a  range  of  several  hun- 
dred feet  and  the  beds  themselves  are  quite  uniform  in 
character,  consisting  of  alternating  thin  layers  of  impure 
limestones  and  marls.  An  attempt  was  made  to  correlate 
the  outcropping  beds  by  close  examination  of  the  layers  ex- 
posed, but  the  result  was  not  very  satisfactory.  A  close 
scrutiny  made  of  each  layer  on  the  section  resulted,  how- 
ever, in  the  finding  of  two  features  that  enabled  me  to 
measure  the  throw  of  the  fault  under  investigation.  Inter- 
bedded  in  the  Boquillas  flags  there  are  some  thin  layers  of 
bentonite,  which  are  quite  persistent  and  can  be  followed 
for  several  miles.  By  comparing  the  distances  between 
these  layers  and  by  taking  note  of  their  individual  thick- 
ness, it  was  possible  to  make  a  correlation  that  seemed  to  be 
correct.  But  the  proof  sought  fell  just  short  of  being  cer- 
tain. In  cases  of  this  kind  one  always  looks  for  corrobo- 
rating facts  to  check  one's  conclusions.  I  found  this  check 
in  the  discovery  of  the  layer  which  carries  ice  crystal  mark- 


8                        University  of  Texas  Bulletin          '  ■; 

1 

ings  in  these  beds.     The  layer  had  a  definite  relation  to  the  ] 
seams  of  bentonite,  and,  with  this  additional  evidence,  I  | 
was  confident  there  was  no  possible  chance  of  a  mistake.  i 
It  enabled  me  to  locate  not  only  the  right  horizon  but  also  ; 
a  horizon  in  the  underlying  heavy  Comanchean  limestone, 
which  is  water-bearing,  and  which  must  be  avoided  to  pre- 
vent serious  injury  to  the  underground  operations.     I  need  , 
not  add  that  the  information  obtained  was  of  real  practical 
value  in  this  case.  j 


PLATE  I 


Plate  I.  Forms  of  frost  cracks  seen  on  the  exposed  flat  bedding 
plane  of  a  block  of  Dakota  sandstone  in  a  ravine  a  few  miles  south- 
west of  Minnekahta,  South  Dakota.  As  sketched  in  the  field.  Nat- 
ural size. 


PLATE   I 


PLATE  II 


% 


Plate  II.  Photographs  of  fossil  imprints  of  ice  crystals  on  flags  of 
the  Eagle  Ford.  The  upper  rock  shown  in  the  Plate  is  from  the 
south  side  of  Cuesta  Blanca  in  Brewster  County,  Texas,  and  shows 
casts  of  crystals  which  represent  fillings  of  sandy  mud  projecting 
slightly  down  into  an  underlying  bed  of  more  argillaceous  material. 
The  lower  part  of  the  figure  shows  a  similarly  marked  flag  from 
the  same  formation  at  a  point  about  five  miles  north  of  the  old 
Boquillas  postofiice  near  Tornillo  Creek,  east  of  the  Chiscs  Moun- 
tains, in  Texas.  Here  are  seen  the  original  grooves  made  by  the 
ice  on  a  layer  of  muddy  material  later  buried.     Slightly  reduced. 


PLATE  II 


PLATE  III 


Plate  III.  Photograph  of  fossil  casts  of  a  close  tangle  of  ice  crys- 
tals seen  in  a  stony  calcareous  layer  in  the  Eagle  Ford  shale  in 
Walnut  Creek,  about  eight  miles  north  of  Austin,  Texas.  This  tangle 
is  closer  than  any  of  the  recent  ice  crystal  marks  figured  hex'e,  but 
equally  closely  grown  crystals  have  been  seen  by  the  writer  on  frozen 
mud  in  Illinois.     Natural  size.      Compare  with  Plate   VIII. 


PLATE  III 


PLATE  IV 


Plate  IV.  Photograph  of  fossil  casts  of  ice  crystals  seen  on  some 
stony  flags  in  the  upper  part  of  the  Eagle  Ford  at  Fossil  Knobs, 
about  two  miles  northwest  of  the  Chisos  Mine  in  Brewster  County, 
Texas.  These  may  be  characterized  as  relatively  short  and  scattered. 
This  shows  ridges  projecting  into  the  grooves  formed  by  ice  crystals 
on  the  surface  of  a  muddy  layer  originally  underlying  the  layer  photo- 
graphed.    Slightly  reduced. 


r 


PLATE  IV 


\:  i 


PLATE  V 


Plate  V.  Photograph  of  fossil  casts  of  ice  crystals  seen  on  the 
under  side  of  flaggy  layer  of  calcareous  sandy  rock  in  the  upper  part 
of  the  Eagle  Ford  at  Fossil  Knobs,  about  two  miles  northwest  from 
the  Chisos  Mining  Company's  property,  Brewster  County,  Texas. 
It  will  be  seen  that  some  of  the  crystals  are  gently  curved.  Similar 
curving  crystals  are  also  seen  in  the  figures  showing  recent  growths 
at  Rock  Island,  Illinois.     Compare  with  Plate  IX.     Slightly  reduced. 


^ 


PLATE  V 


■'\ 


,1 


PLATE  VI 


Plate  VI.  Photograph  of  a  thin  flag  of  sandy  limestone  from  the 
Eagle  Ford  at  Fossil  Knobs  in  Brewster  County,  showing  molds  left 
by  ice  crystals. 


PLATE  VI 


PLATE  VII 


Plate  VII.  Photographs  of  three  fragments  of  flags  showing  casts 
of  ice  crystals  on  the  under  side.  All  observations  made  on  crystals 
of  this  kind  indicate  local  differences  in  the  forms  of  ice  crystals 
presumably  due  to  differences  in  the  rate  of  freezing,  in  the  texture 
of  the  mud  and  probably  in  variations  in  water  content  of  the  mud. 
Some  crystals  in  the  locality  from  which  these  specimens  came,  show 
pinnate  secondary  growths.  Specimens  shown  here  are  from  near 
the  upper  part  of  the  Eagle  Ford  at  a  point  about  two  miles  north 
from  the  Chisos  Mining  Company's  property,  Brewster  County,  Texas. 
Slightly  reduced. 


PLATE  VII 


PLATE  VIII 


Plate  VIII.  Photograph  of  a  cast  made  by  pouring  plaster  over  a 
surface  of  mud  in  which  ice  crystals  had  recently  formed,  in  Rock 
Island,  Illinois,  after  the  ice  in  the  crystals  had  been  removed  by 
slow  natural  sublimation  into  the  atmosphere,  leaving  open  cracks 
in  the  mud.  The  comb-like  ridges  on  the  plaster  cast  have  the  form 
of  the  ice  crystals.     Compare  with  Plate  III. 


PLATE  VIII 


:i1>.' 


\<. 


fV'i 


PLATE  IX 


Plate  IX.  Photograph  of  a  cast  made  by  pouring  plaster  over  a 
surface  of  mud  in  which  ice  crystals  had  formed,  in  Rock  Island, 
Illinois,  soon  after  the  ice  in  the  crystals  had  been  removed  by 
slow  natural  sublimation  into  the  atmosphere,  leaving  open  cracks 
in  the  mud.  In  the  locality  where  this  cast  was  made,  the  crystals 
were  relatively  slender,  distant,  and  some  gently  curved,  like  those 
seen  in  Plate  V.     Slightly  reduced. 


PLATE  IX 


PLATE  X 


Plate  X.  Photograph  of  a  cast  made  by  pouring  plaster  over  a 
surface  of  mud  in  which  ice  crystals  had  recently  formed,  in  Rock 
Island,  111.,  and  where  they  had  later  been  removed  by  natural 
sublimations  into  the  atmosphere,  leaving  open  cracks  in  the  mud. 
It  will  be  seen  that  the  crystal  growth  in  this  case  involves  an  x-like 
or  radiating  pattern  formed  of  relatively  very  slender  forms  that 
almost  everywhere  are  very  gently  curved  somewhat  reminding  of 
the  slender  thread-like  crystals  sometimes  seen  in  frost  on  windows. 
I  have  not  yet  seen  any  similar  fossil  crystal  growths  as  slender  as 
these.     Slightly  reduced. 


PLATE  X 


'■^^.: 


i^- 


1-^ 


m 


RETURN     EARTH  SCIENCES  LIBRARY 

TO— #►     230  Earth  Sciences  BIdq.    642-2997 

LOAN  PERIOD  1 
-      1 4  DAYS 

2 

3 

4 

5 

6 

ALL  BOOKS  MAY  BE  RECALLED  AFTER  7  DAYS 
Books  needed  for  doss  reserve  ore  subject  to  immediate  recoil 

DUE  AS  STAMPED  BELOW 

UNIVERSITY  OF  CALIFORNIA,  BERKELEY 
FORMNO.  DD8    4m    11/78            BERKELEY,  CA  94720 

PS 

li-di 


